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Study Finds Indoor Air Problems Common in U.S. Schools

U.S. Government studies have shown that one in five schools has indoor air quality (IAQ) problems, but such problems can be improved through use of active humidity control and continuous ventilation, according to new research.

More than 8 million students are affected by problems with IAQ, according to U.S. government research outlined in an article published in IAQ Applications by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Problems can include drowsiness, lack of concentration or headaches, which affect comprehension and motivation of students. Researcher Charlene Bayer, Ph.D., Georgia Tech Research Institute, said IAQ should be a top priority in schools because children, who are still developing physically, are more likely to suffer due to indoor pollutants. Also, the number of children with asthma has increased 49% since 1982.

Researchers are studying the impact of continuous ventilation (where the system runs 24 hours a day) and active humidity control on IAQ in schools.

Problems with IAQ may stem from school personnel not understanding how to operate ventilation systems and introducing contaminants, such as plug-in chemical deodorizers and art supplies, into classrooms.

Bayer said use of active humidity control and continuous ventilation can help improve problems with IAQ. Research showed that pollutant levels dropped when higher outdoor air was delivered.

Based on a study of existing IAQ research, Bayer and her co-authors suggest that most IAQ problems in schools can be avoided by:

Providing an adequate amount of outdoor air on a continuous basis;

Controlling humidity in the space so that it is usually between 30% and 60% relative humidity;

and Providing a level of particulate filtration efficiency for outdoor air adequate to prohibit most mold spores and fungi from entering the HVAC system.

One reason that IAQ should be considered a top priority in the school environment is that children are still developing physically and are more likely to suffer the consequences of indoor pollutants. Another reason is that the number of children suffering from asthma is up 49$ since 1982, according to the American Lung Association. Asthma is the principal cause of school absences, accounting for 20% of lost school days in elementary and high schools (Richards 1986). Richards also notes that allergic disease (nasal allergy, asthma, and other allergies) is the "number one" chronic childhood illness, accounting for one-third of all chronic conditions occurring annually and affecting 20% of school children.

Children from birth to age 10 have three times as many colds as adults (Tyrrell 1965). School facilities, by design, are densely populated, making the task of maintaining an acceptable indoor environment more difficult than in many other types of facilities. Another consideration is that the sole purpose of a school facility is to foster the learning process, which is impacted directly by the quality of the indoor environment (HPAC 1990; Dozier 1992; Boone 1997).

Finally, most individuals have experienced drowsiness, lack of concentration, or headaches in a classroom or auditorium, and therefore understand the impact these symptoms have on comprehension and motivation. Research is needed to determine if ventilation rates promote the best learning and healthiest environment for school children. Southern, humid climates present a challenge to school designers, contractors, and facility maintenance staff to bring in sufficient outside air to handle the pollutant load while simultaneously controlling humidity levels between 40% to 60% RH ? the ASHRAE recommended inside relative humidity level.

The U.S. Government's General Accounting Office issued reports stating that one in five schools in the United States has IAQ problems (GAO 1995, 1996) affecting 8.4 million students. According to the same studies, 36% of the schools surveyed listed HVAC systems as a "less-than-adequate building feature." The report also suggested that there appears to be a correlation between unsatisfactory IAQ and the proportion of a school's students coming from low-income households.

Bascom (1997) states that "schools are facing two epidemics: an epidemic of deteriorating facilities and an epidemic of asthma among children." She notes that although clinicians are trying to educate school facility managers and administrators about environmental control measures for children with asthma, these clinicians have little information about the conditions and practical and financially feasible environmental controls that can be done by school systems. The schools are ill equipped to receive the recommendations, assess their reasonableness, and effect the recommendation at a reasonable cost. Bascom calls for the development of task forces to assemble the necessary expertise to solve these environmental problems. She points to the need for a controlled IAQ research study so that effective IAQ plans can be developed and implemented.

Daisey and Angell (1998) conducted a survey and critical review of the existing published literature and reports on IAQ, ventilation, and building-related health problems in schools. They found that the types of health symptoms reported in schools are very similar to those defined as "sick building syndrome" (SBS), although this finding may be due, at least in part, to the type of health symptom questionnaires used. Some of the symptoms (e.g., wheezing) are indicative of asthma. In the studies in which "complaint" and "non-complaint" buildings were compared, complaint building usually had a higher rate of health-related symptoms.

The major building-related problem identified by Daisey and Angell was inadequate outdoor air ventilation. Water damage to the building shells of schools, leading in turn to mold contamination and growth, was the second most frequently reported building-related problem. The root cause of many of the ventilation and water-damage problems in the schools was inadequate and/or deferred maintenance of school buildings and HVAC systems.

Daisey and Angell concluded that considerable qualitative information now exists on health complaints, ventilation, and IAQ problems in complaint schools. It is unknown what fraction of schools are experiencing IAQ and ventilation problems and related health problems. There is also a lack of the scientifically rigorous and quantitative information on causal relationships between health symptoms, exposure, and dose-response relationships that is needed to establish health standards for the protection of children in schools. The effectiveness and the cost/benefit ratio of various remedial actions undertaken to solve problems in specific schools remain largely unknown.

The report recommended the following research:

Determine more quantitatively the degree to which IAQ problems in schools increase asthma, SBS symptoms, and absentee rates of students.

Identify the specific agents that cause health effects and determine exposure and dose-response relationships for those pollutants that are the most significantly related to health symptoms.

Determine whether learning can be increased significantly through improved IAQ.

Determine the cost-effectiveness of various remediation measures undertaken to solve problems in complaint schools through intervention studies in which changes in health symptoms and test scores are measured before and after remediation.

Determine the costs of deferred building maintenance with respect to health and learning in students.

Determine the viability of using CO2 detectors and other types of sensors to routinely control ventilation and to provide an indication of low ventilation.

Develop improved sampling and analysis methods for bioaerosols.

Developed low-cost samplers for measuring six-hour exposures to other key indoor pollutants, such as aldehydes, that may be contributing to the kinds of symptoms observed in problem school.

The researchers at the Georgia Tech Research Institute (GTRI) undertook a Department of Energy (DOE) sponsored research project to try to answer some of the questions about building systems and IAQ in schools. The project is investigating the impact of continuous ventilation and active humidity control on the IAQ in schools, and is providing baseline data in non-complaint schools.

Ten schools in Georgia were selected, which did not have known IAQ complaints. Five of the schools had desiccant-based humidity control systems and five of the schools did not. The schools are matched in pairs as closely as possible. Continuous monitors for measuring CO2, temperature, and humidity were placed in the schools for approximately a year. Additionally, on-site IAQ sampling was conducted four times in each of the schools for VOCs (speciated and total), microbially produced VOCs (MVOCs), particles, aldehydes and ketones, airborne microbes, CO2, CO, temperature, relative humidity, and air change rate. Three inside and two outside samples were taken in each school. Additionally, diffusion tube VOC samplers were placed in the schools and 30-day average VOC samples were collected throughout the testing year. The data still are being analyzed, but several results are reportable now.

One of the most important findings of this research project is the need for school facility managers and maintenance personnel to understand the functioning and purpose of the school ventilation system, particularly the differences between the newer, nonconventional systems and the older, more common systems. It was difficult to ascertain that the desiccant systems were operating as designed in the schools. In two schools, the desiccant systems were not installed correctly and were not operating correctly early in the research project. None of the on-site maintenance staff understood that the desiccant systems were designed to operate continuously so that humidity constantly was controlled and continuous ventilation was supplied. Frequently, the desiccant systems were found turned off. The maintenance staff remarked that since the humidity was not high on those days, it was not necessary to operate the system.

In each of the schools, there was no understanding by the teaching and administrative staff of the need to control contaminant sources indoors. In one room of one of the schools, the teacher had five plug-in chemical deodorizers operating simultaneously. Almost every teacher in every school had a least two of these deodorizing units operating in the classroom. Painting and cleaning often were done during school hours. Many of the art supplies were contributors to the indoor contaminant load. Copiers and other office equipment were placed wherever there was room, with no planning or exhaust for fumes.

Teachers, particularly in the schools without desiccant systems, preferred to open the windows to their rooms, if the rooms had operable windows. Individual control of the temperature was expressed to be important to schools staff. In one of the schools with a desiccant-based system, the teachers were unhappy with the air in the school, until individual thermostats were installed in each classroom. Once this was done, the teachers had no more air quality complaints.

In general, the schools with the desiccant-based systems appeared to have better indoor environments, due in part to the increased ventilation. Figure 1 shows the average cfm/student of outdoor air delivery calculated from the continuous monitoring data. Figure 1 shows that none of the schools with conventional HVAC systems supplied outside air at the ASHRAE recommended 15 cfm/person. The outside air delivery rate ranged from 4.1 to 9.1 cfm/person in these schools. Only School P, with the conventional system, had an average outside air supply of 9.2, and this primarily was because the teachers kept the windows open almost all of the time that school was in session.

By contrast, the cfm/student in the schools with the desiccant systems had an outdoor air supply range of 7.9 to 14.4 cfm/student. The higher ventilation rate lowered the average pollutant levels in these schools. This is shown in Figures 2 through 7. Figure 2 shows the average CO2 levels above the outside levels found in the schools during the four on-site sampling periods.

The schools with the desiccant-based systems had lower inside CO2 levels, ranging from 758 to 1,302 ppm above the outside concentration. This also was shown with the continuous monitors. The average CO2 levels inside the schools with the conventional system, above the outside CO2 levels, ranged from 1,349 to 2,025 ppm. The effect of the outdoor air supply per student on the CO2 concentration is shown in Figure 3. The figure shows that School L, with the highest outdoor air supply per student, had the lowest inside CO2 levels. School L also was the only school in which the desiccant systems operated continuously throughout the entire project. Schools A and E, with the lowest outdoor air supply per student, had the highest inside CO2 concentrations. As can be seen in Figure 3, the inside average airborne microbial concentration was significantly less than that in the outside for each of the schools.

No obvious differences existed between the average airborne microbial concentrations in the schools with the desiccant-based systems and those with the conventional systems from only the airborne microbial concentrations data, Figure 4. However, comparing the airborne microbial concentrations to the outdoor air supply per student indicates that a higher ventilation rate can impact the airborne microbial concentration when there is adequate humidity control, Figure 5. (Figure 8 shows that the average relative humidity levels, as measured during the on-site sampling, in each of the schools ranged between 42% to 57%). The average TVOC concentrations tended to be lower in the schools with the desiccant-based systems (Figure 6 and 7), but in six out of 10 of the schools, the average TVOC concentration exceeded 1,000 mg/m3. Many of the detected TVOCs are the result of deodorizers and other cleaning products used in the schools.

School L had the highest air change rate and the lowest average concentrations of CO2, TVOCs, and airborne microbes. Figure 8 shows the average measured on-site temperature, dew point, and relative humidity. The relative humidity in the schools ranged between 42% to 57%, with School L having the lowest relative humidity of 42%. No obvious correlation existed between the average temperature, dew point and relative humidities, as measured during the on-site sampling, and the conventional or non-conventional system. This may have been a result of teachers opening windows and doors or improper or lack of operation of the desiccant system.

The continuous monitoring data, which is incompletely analyzed at this time, indicates wider differences between the schools with the conventional systems and the desiccant systems. The schools with the conventional systems are bringing in lower amounts of outside air that has to be conditioned than the school with the desiccant systems. The desiccant systems were delivering as much as three times more outside air while maintaining the indoor releative humidity at the same or better percentage than the conventional systems. Statical data correlations are ongoing and will be presented in subsequent papers.

Written by: Charlene W. Bayer, Ph.D

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